[analysis_server] Fix duplicate diagnostic/lint names in analysis_options completion

Some of the diagnostic names are used by multiple diagnostics (for example `extendsDeferredClass` and `implementsDeferredClass` both use `SUBTYPE_OF_DEFERRED_CLASS` so they need to be de-duped when adding to code completion.

Fixes #61434

Change-Id: Ie0875c8aadb5543b524fc8730c2860e9ac73d496
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/448040
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Brian Wilkerson <[email protected]>
Reviewed-by: Samuel Rawlins <[email protected]>

Author: DanTup

pkg/analysis_server/lib/src/services/completion/yaml/analysis_options_generator.dart

@@ -73,12 +73,13 @@ class _ErrorProducer extends KeyValueProducer {
 
   @override
   Iterable<CompletionSuggestion> suggestions(YamlCompletionRequest request) {
-    return [
+    // There may be overlaps in these names, so use a set.
+    var names = {
       for (var diagnostic in diagnosticCodeValues)
-        identifier('${diagnostic.name.toLowerCase()}: '),
-      for (var rule in Registry.ruleRegistry.rules)
-        identifier('${rule.name}: '),
-    ];
+        diagnostic.name.toLowerCase(),
+      for (var rule in Registry.ruleRegistry.rules) rule.name,
+    };
+    return {for (var name in names) identifier('$name: ')};
   }
 }
 

pkg/analysis_server/test/src/services/completion/yaml/analysis_options_generator_test.dart

@@ -8,6 +8,7 @@ import 'package:analyzer/error/error.dart';
 import 'package:analyzer/src/analysis_options/analysis_options_file.dart';
 import 'package:analyzer/src/lint/linter.dart';
 import 'package:analyzer/src/test_utilities/lint_registration_mixin.dart';
+import 'package:collection/collection.dart';
 import 'package:linter/src/rules.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
@@ -77,7 +78,7 @@ analyzer:
     assertSuggestion('annotate_overrides: ');
   }
 
-  void test_analyzer_errors_nonDuplicate() {
+  void test_analyzer_errors_excludesExisting() {
     getCompletions('''
 analyzer:
   errors:
@@ -87,6 +88,20 @@ analyzer:
     assertNoSuggestion('dead_code');
   }
 
+  void test_analyzer_errors_noDuplicates() {
+    getCompletions('''
+analyzer:
+  errors:
+    ^
+''');
+    var duplicateCompletions =
+        groupBy(
+          results.map((result) => result.completion),
+          (result) => result,
+        ).entries.where((entry) => entry.value.length > 1).keys;
+    expect(duplicateCompletions, isEmpty);
+  }
+
   void test_analyzer_errors_severity() {
     getCompletions('''
 analyzer: